Add --detect-speed-hint for improving test time for speed detection.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/audiowmark.cc

@@ -565,6 +565,8 @@ parse_add_options (ArgParser& ap)
 void
 parse_get_options (ArgParser& ap)
 {
+  float f;
+
   ap.parse_opt ("--test-cut", Params::test_cut);
   ap.parse_opt ("--test-truncate", Params::test_truncate);
 
@@ -580,6 +582,10 @@ parse_get_options (ArgParser& ap)
     {
       Params::detect_speed = true;
     }
+  if (ap.parse_opt ("--detect-speed-hint", f))
+    {
+      Params::detect_speed_hint = f;
+    }
 }
 
 int

src/wmcommon.cc

@@ -26,6 +26,7 @@ bool   Params::mix             = true;
 bool   Params::hard            = false; // hard decode bits? (soft decoding is better)
 bool   Params::snr             = false; // compute/show snr while adding watermark
 bool   Params::detect_speed    = false;
+double Params::detect_speed_hint = -1;
 int    Params::have_key        = 0;
 size_t Params::payload_size    = 128;
 bool   Params::payload_short   = false;

src/wmcommon.hh

@@ -42,7 +42,9 @@ public:
   static           bool hard;                      // hard decode bits? (soft decoding is better)
   static           bool snr;                       // compute/show snr while adding watermark
   static           int  have_key;
+
   static           bool detect_speed;
+  static           double detect_speed_hint;       // for debugging --detect-speed
 
   static           size_t payload_size;            // number of payload bits for the watermark
   static           bool   payload_short;

src/wmget.cc

@@ -1052,9 +1052,28 @@ detect_speed (const WavData& wav_data, double center, double step, int n_steps,
   WavData wd_truncated = truncate (wav_data, seconds * 1.5);
   double best_speed = 1.0;
   double best_quality = 0;
+
+  int best_hint_step = 0;
+  if (Params::detect_speed_hint > 0)
+    {
+      double best_dist = 1000;
+      for (int p = -n_steps; p <= n_steps; p++)
+        {
+          double dist = fabs (center * pow (step, p) - Params::detect_speed_hint);
+          if (dist < best_dist)
+            {
+              best_hint_step = p;
+              best_dist      = dist;
+            }
+        }
+    }
   printf ("## range [%f..%f], n_steps=%d\n", center * pow (step, -n_steps), center * pow (step, n_steps), n_steps);
   for (int p = -n_steps; p <= n_steps; p++)
     {
+      if (Params::detect_speed_hint > 0)
+        if (abs (p - best_hint_step) > 2)
+          continue;
+
       double speed = center * pow (step, p);
 
       WavData wd_resampled = wd_truncated;